1. Field of the Invention
The present invention relates to connectors and specifically to high speed, shielded connectors having one or more integrated PCB assemblies.
2. Brief Description of Prior Developments
Connectors, having insulative bodies and individual metal terminals are now widely used and available in many different configurations. For most connector structures the usual method of manufacture comprises stitching or insert molding terminals into a suitable housing. The manufacturing process may also include a terminal tail bending operation, especially for right angle connectors. Connectors for high-frequency applications present additional requirements. In this regard, controlled-impedance terminal sections with ground shielding options are preferred. Towards this end, it is known to subdivide the manufacture of such a connector into one part for accommodating contact terminals for mating contact with the contact terminal of a mating connector and a separate part for the tail end. Separate shielding casings, if required in a right angled configuration, may be provided around each of the terminals within the connector. Although connectors manufactured as described above operate satisfactorily, the manufacturing costs are high.
U.S. Pat. No. 4,571,014 shows a different approach for making backplane connectors using one or more PCB assemblies. Each of the PCB assemblies comprises one insulated substrate, one spacer, and one cover plate, all of which are attached to one another. The insulating substrate is provided with a predetermined pattern of conducting tracks, while ground tracks are provided between the conducting tracks. The conducting tracks are connected at one end to a female contact terminal and at the other end to a male contact terminal. Each of the cover plates is a conductive shield member.
In the arrangement according to U.S. Pat. No. 4,571,014, the circuit substrates are arranged with the sides bearing the conductive tracks all facing in the same direction. The cover plates/shields are each interleaved between adjacent substrates. While such an arrangement produces a plurality of individual shielded tracks, it does not present the possibility for creating impedance matched pairs of conductive tracks through the connector, in a twinax configuration. Twinax connectors are often utilized in combination with twisted pair cable. Such twisted pair cables usually have a plurality of pairs of identical conductors twisted along the signal transmission length. Such a conductor pair has the signal over the two conductors as differential pair; this conductor pair (and possibly several twisted pairs) is enclosed within an outer copper shielding braid to form a cable. Often each twisted pair may have an individual drain wire. Because the electromagnetic flux generated on the twisted pair of a conductor are equal in magnitude and opposite in direction, effectively they cancel each other. Extending this concept to a pair of twinax connector contacts, this can be envisaged as two adjacent, spaced contact elements contained within an outer (rectangular cross-section) grounding shell. This is a relatively inexpensive method to maintain signal quality through an interconnection. Often this is referred to a "balanced pair" interconnection. Use of such twinax interconnection termination is often related to the use of cable, but similarly a twinax connector may be terminated on a PCB. In the latter case, instead of the cable twisting, the connector can be mounted on a PCB having pairs of identical tracks which are located spatially adjacent to each other, usually as part of a multi-layered structure.
Further, U.S. Pat. No. 4,571,014 discloses primarily a backplane interconnection and not a cable-to-cable or cable-to-board interconnection.
Published European Patent No. 0 442 643 discloses a cable connector formed of a plurality of shielded PCB assemblies. However, this connector does not use mirror image PCB orientation for forming twinax connectors. Further, this design utilizes a metal shield that envelops each PCB assembly.
PCT Patent Application Ser. No. US96/11214 filed Jul. 2, 1996 (the disclosure of which is incorporated therein by reference) discloses board to board connectors made from stacked modules, each module being formed of a printed circuit board assembly and a cover. This application discloses high speed board to board connectors that have relatively low manufacturing costs.